As apparatuses that store a large amount of information, library apparatuses are known. Library apparatuses each store, for example, a plurality of cartridges in which recording media are stored, and allow information to be read from or written to the cartridges. Some library apparatuses are provided with removable magazines used to insert or remove a plurality of cartridges with a single operation. Such apparatuses are referred to as magazine-type library apparatuses.
The magazine has a plurality of slots arranged side by side in a direction parallel to the longitudinal direction of the library apparatus. Each slot stores one of the cartridges. In some cases, a plurality of rows of the arranged slots are stacked one on top of the other.
The library apparatus is equipped with a transportation mechanism therein that includes a hand mechanism to hold cartridges. The hand mechanism extends hands in a direction perpendicular to a direction in which slots are arranged to remove a target cartridge from a corresponding one of the slots. The removed cartridge is held by the hand mechanism and transported to a recording and playback device using the transportation mechanism. After the cartridge is used, the transportation mechanism returns the cartridge from the recording and playback device to the slot in which the cartridge existed before the cartridge was removed.
In order to exchange the cartridge stored in the magazine, the magazine that stores the target cartridge is removed from the library apparatus. An operator exchanges the cartridge of the removed magazine. Accordingly, every time the magazine is loaded in the library apparatus, the library apparatus usually recognizes what cartridge is stored in what slot corresponding to the exchange of the cartridge.
For this reason, each of the cartridges has a bar code label, which is an example of an identifier, on the rear surface thereof. On the bar code label, characters or an image that indicate a volume number, which identifies a particular cartridge, are printed as bar code information.
The volume number is expressed by, for example, a number that is a combination of a specified number of specified alpha-numeric characters and symbols. In order to read this bar code label using a bar code reader, a magnetic tape cartridge is stored in the slot by the operator such that the bar code label is directed to the opening side of the slot.
The bar code reader is mounted in the cartridge transportation mechanism. When the magazine has been loaded, the transportation mechanism moves to each slot to position the bar code reader. The bar code reader reads the bar code label of the cartridge at each slot.
A control portion of the library apparatus obtains bar code information of each bar code label. By doing this, the controller may recognize what volume number of cartridge is stored in what slot. An operation in which identifiers of cartridges are read to recognize the types and storing positions of the cartridges as described above is referred to as an inventory operation.
Japanese Laid-open Patent Publications No. 2003-59143 and No. 8-53205 are examples of disclosed related art.